linux-kernel - Re: [PATCH] x86_64: set cfg_size for AMD Family 10h in case MMCONFIG is used

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Message-ID: <86802c440709131222v6e819e4ayed27430ba4e61154@mail.gmail.com>
Date:	Thu, 13 Sep 2007 12:22:51 -0700
From:	"Yinghai Lu" <yhlu.kernel@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	"Andi Kleen" <ak@...e.de>, "Greg KH" <greg@...ah.com>,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Jeff Garzik" <jeff@...zik.org>, "Martin Mares" <mj@....cz>,
	"dean gaudet" <dean@...tic.org>,
	"Robert Richter" <robert.richter@....com>,
	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86_64: set cfg_size for AMD Family 10h in case MMCONFIG is used

On 9/13/07, H. Peter Anvin <hpa@...or.com> wrote:
> Yinghai Lu wrote:
> >
> > BIOS guys also said that fam 10h need mmconfig via eax accessing, may
> > need OS do sth, so it is safe to stay with MCFG entry for SB like
> > mcp55...
> >
> > but latest kernel already have that workaround to make mmconfig via eax...
> >
>
> This is actually a good point.  Since the CPU vendor managed to
> completely fuck up the operation of MMCONFIG itself on this CPU (it's a
> *MEMORY REFERENCE*, guys!), it is actually to be expected and prudent
> that BIOS vendors will drop the MCFG entry.  MMCONFIG doesn't actually
> work on this CPU for any system software which doesn't already know to
> work around this particular piece of severe braindamage;
> standards-complicant MMCONFIG isn't supported at all.

if other mmconfig device on x86 is sick of accessing via eax, may need
to provide one fam10h_pci_mmcfg to be assigned to raw_pci_ops instead
and leave pci_mmcfg to default behavior ( *MEMORY REFERENCE*).

YH
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